This paper discusses the evolution of the foggara in time and the methods adopted by farmers to increase the water parts of owners. Field works were conducted in 2007, 2008, 2009 and 2010 in the oases of Timimoun and Adrar. Over 100 foggaras were visited. Surveys and interviews with the populations and the owners were conducted. Two ancestral methods are used by the farmers to increase the discharge of the foggara. This is an extension of part of the drainage gallery and the addition of one or more branch in the main gallery. Over time, the foggara to a single gallery evolves towards a foggara to several galleries in the form a ramified network of galleries.
This paper introduces a combined modelling approach using a simple water budget model (THC-model) and a 3D reservoir sedimentation model (MOHID Water) to adapt reservoir operation and visualise their effects on the sediment deposition. By this, an effective combined sediment-water management can be identified under semi-arid conditions for dry, median and wet years. Results are presented for the reservoirs of the Tuyamuyun Hydro-Complex (THC), which is located in the lower Amu Darya River. The determination of the actual and usable reservoir storage volume shows that siltation will significantly adversely affect the ability of the in-stream Channel Reservoir to regulate seasonal demand for both irrigation and municipal water supply. However, modelling scenarios results confirm the effectiveness of adapted operation rules for the THC reservoirs and show that the operation of large dams could be modified according to a combined sediment-water management. The experience gained during this study emphasizes the fact that the concept of a combined reservoir management of sediments as well as water can be an efficient measure to improve the sustainable long-term use of reservoirs and to contribute towards a safe water supply in water crisis regions.
A weekly irrigation planning LP model is formulated for determining the optimal cropping pattern and reservoir water allocation for an existing storage based irrigation system in India. Objective of the model is maximization of net annual benefit from the project. In an irrigation planning of a storage based irrigation system, initial storage of the reservoir at the beginning of the reservoir operation, expected inflows into the reservoir during each intraseasonal period, capacity of channels, crop calendar and yield response to water deficit in each growth stage of crop play a vital role in deciding acreage and water allocation to each crop. The planning model takes into account yield response to water deficit in each intraseasonal period of the crop, expected weekly inflows entering into the reservoir, storage continuity of reservoir, land and water availability, equity of water allocation among sub areas and proportionate downstream river release. One year comprising of 52 weeks is considered as planning horizon. To account for uncertainty in water resources availability, the model is solved for four levels of reliability of weekly inflows entering into the reservoir (90%, 85%, 80% and 75%). Alternative optimal cropping patterns and weekly releases to crops grown in each sub area under each main canal are obtained for various states of initial storage at the beginning of reservoir operation and for various levels of weekly inflows into the reservoir. Results reveal the importance of initial state of reservoir storage for feasible solution and shows the impact on cropping pattern with the change in initial storage of reservoir for different levels of reliability of weekly inflows.
Chemigation is used to apply a wide variety of chemicals to many kinds of crops through different types of irrigation systems. The bypass flow chemical injector using the pipe bend devices is a simple pressure differential method. The hydraulic experiments of pipe bend devices with different shape and size crests were conducted using 30 mm internal diameter pipe bend devices without crest (bypass design No.1), with one 5 mm size crest on the outer wall (bypass design No.2), with one 10 mm size crest on the outer wall (bypass design No.3) and with two10 mm size crests on both inner and outer walls inside the pipe bend (bypass design No.4). Relations among the main pipe flow rate (Q), the bypass flow rate (q), the pressure difference without bypass flow (DH 0 ) and the pressure difference with bypass flow (DH) between inside and outside of a pipe bend were investigated. The results show that the magnitudes of the parameters DH/Q 2 and q/Q are ranked among different flow types as: No.4 > No.3 > No.2 > No.1, and they are also constant coefficients for bend pipe devices. Then, after a chemical tank or batch tank added in the bypass route, the chemical or fertilizer can be injected into irrigation systems by bypass flow across a pipe bend device at a constant flow rate, but the chemical content is being diluted with time as water flows into the tank and mixes with the original solution. In one irrigation system, the purpose of bypass flow rate can be reached using a pipe bend devices with and without different shape and size crests.
Irrigation tanks in India are common property resources. Tanks provide not only for irrigation, but also forestry, fishing, domestic water supply, livestock, and other uses. Using empirical results from a study of tank performance from 80 tanks in Tamil Nadu, South India in two time period: 1996-97 and 2009-10, this paper evaluates tank irrigation system performance in terms of economic output and revenue generation forirrigation and other uses. The results indicate that irrigation and other productive uses put together raised the total value of output at tank level by 12 % in 1996-97 and just 6 % in 2009-10. This may suggest that tank multiple use values are small and getting smaller, and therefore not worth consideration. However, it was also found that, while declining in absolute terms, non-irrigation uses provided the majority of tax revenues and still more than cover government's operation and maintenance expenditure (O&M) budget. This finding provides another reason to consider multiple use values and their linkage with overall system viability.
A linear programming model was developed to assess the impact of different water prices on cultivated areas, irrigation water demand, net income and optimal cropping pattern in the Northern Jordan Valley (NJV). The results reveal that the price for irrigation water does not reflect any elasticity in the range of water prices between 0.01 and 0.06 JD/M3 indicating constant real economic water price of 0.06 JD/M3. The change in cultivated areas as well as water demand (reduction) starts at water price 0.07 JD/M3. The expected reductions under optimal cropping patterns are 5%, 24%, and 60% for cultivated area and 4.7%, 18.9%, and 31% for water demand with water prices at 0.07, 0.1, and 0.16 JD/M3, respectively. Significant reductions in net incomes are resulted with increasing water prices over current average water price of 0.025 JD/M3. The expected reductions in net incomes are 33.6%, 53.8%, and 81.4% at water prices 0.07, 0.1, and 0.16 JD/M3, respectively. This result reflects the low land profitability as a result of low land productivity and/or low farm gate sale prices for most crops grown in NJV. The study also shows the inconsistency in quantity of water supplied and water demanded, leading to unbalanced water budget on monthly level and inconsequence, a noticeable waste in the quantity of available water during winter months, although there is a net surplus of water over the year. While the findings of this research reveal that a water price in the range of 0.07–0.1 JD/M3 does not significantly influence the farmers' socio-economic parameters in the NJV, it may help reach the stated goal of saving water especially when monthly distributions of irrigation water are based on real crops water demands and actual cropping patterns.
It is well-known that major irrigation projects have a strong scale economy, handicapping irrigation development in sub-Saharan Africa (SSA) because of the difficulty in formulating large-scale projects. Using project-level investment cost and performance data of major and minor irrigation projects, this paper examines the causes of the economy of scale phenomenon. We find that strong scale economy exists not only for major but also for minor projects, i.e., small- and micro-scale, projects. This is largely because of the existence of indivisible overhead costs such as high-opportunity-cost human resources for planning, designing and engineering management and supervision. We also find that large differences between major and minor projects in the absolute level of overhead as well as construction costs creates a strong scale diseconomy and results in better performance of minor projects. The advantage of minor projects holds even when their higher risk associated with the water source is taken into consideration. We argue that there is an urgent need to promote irrigation development in SSA through developing minor projects, and to reduce the heavy burden of overhead costs by developing the capacity of human resources at the national, local and farmer levels in the fields of irrigation engineering, irrigation agronomy, institutional development, and micro water management technologies.
Water consumed through evapotranspiration (ET) impacts local and regional hydrologic regimes on various spatial and temporal scales. Estimating ET in the Great Plains is a prerequisite for effective regional water resource management of the Ogallala (High Plains) Aquifer, which supplies vital water resources in the form of irrigation for extensive agricultural production. The Sand Hills region of Nebraska is one of the largest grass-stabilized eolian (windblown) sand dune formations in the world, with an area of roughly 50,000–60,000 km2 that supports a system of five major land cover types: (1) lakes, (2) wetlands (with lakes, ~5%), (3) subirrigated meadows (water table is within ~1 m of surface; ~10%), (4) dry valleys (water table is 1–10 m below surface; ~20%), and (5) upland dunes (water table is more than 10 m below surface; ~65%). Fully understanding the hydrologic regime of these different ecosystems is a fundamental challenge in regional water resource assessment. The surface energy and water balances were analyzed using Bowen Ratio Energy Balance Systems (BREBS) at three locations: (1) a meadow, (2) a valley, and (3) an upland dune. Measurement of the energy budget by BREBS, in concert with Landsat remote sensing image processing for 2004 reveals strong spatial gradients between sites in latent heat flux that are associated with undulating topographic relief. We find that daily estimates of ET from BREBS measurements and remote sensing agree well, with an uncertainty within 1 mm, which is encouraging when applying remote sensing results across such a broad spatial scale and undulating topography.
Agricultural nonpoint-source pollution is the leading cause of water-quality degeneration of rivers and groundwater. In this context, the coast of Granada province (SE Spain) is economically an important area for the subtropical fruit cultivation. This intensively irrigated agriculture often uses excessive fertilizers, resulting to water pollution. Therefore, a 2-year experiment was conducted using drainage lysimeters to determine the potential risk of nutrient pollution in mango ( Mangifera indica L. cv. Osteen) and cherimoya ( Annona cherimola Mill. cv. Fino de Jete) orchards. These lysimeters were used to estimate the nutrient budgeting for each crop. NO 3 -N, NH 4 -N, PO 4 -P and K losses according to lysimeters were, respectively, 55.1, 12.4, 3.7, and 0.6 for mango and 61.8, 17.8, 4.9, and 0.5 kg ha −1 yr −1 , for cherimoya. NO 3 , concentrations in the leachates ranged from 1.8 to 44.3 mg L −1 , and from 23.0 to 51.0 mg L −1 , for mango and cherimoya, respectively, in some cases exceeding the limits for safe drinking water. PO 4 also exceeded the permitted concentrations related to eutrophication of water, ranging from 0.07 to 0.5 mg L −1 and from 0.12 to 0.68 mg L −1 from mango and cherimoya lysimeters, respectively. With respect to the nutrient balance, N, P, and K removed by cherimoya fruits was 76.4, 5.5, and 22.6 kg ha −1 yr −1 , and for mango fruits 30.2, 3.3 and 27.8 kg ha −1 yr −1 , respectively. Nutrient losses in the leachates were surprisingly low, considering total N, P, and K applied during the year, in mango lysimeters 3.8, 0.11, and 12.6%, and in cherimoya lysimeters 7.7, 0.23 and 16.0%, respectively, indicating a potential soil accumulation and eventual loss risk, especially during torrential rains. Crop coefficient ( Kc ) values of mango trees varied within ranges of 0.35–0.67, 0.55–0.89, and 0.39–0.80 at flowering, fruit set, and fruit growth, respectively. Kc values for cherimoya trees had ranges of 0.58–0.67, 0.61–0.68, and 0.43–0.62 at flowering, fruit set and fruit growth, respectively. In this study, the Kc values of mango and cherimoya were significantly correlated to julian days. Therefore, the estimated WUE in the mango and cherimoya orchards reached 21.2 and 14.0 kg ha −1 mm −1 , respectively. Thus, this study highlights the urgency to establish the optimal use of fertilizers and irrigation water with respect to crop requirements, to preserve surface-water and groundwater quality, thereby achieving more sustainable agriculture in orchard terraces.
The goal of this study was to investigate land use changes in urban and peri-urban Hyderabad and their influence on wastewater irrigated rice using Landsat ETM + data and spectral matching techniques. The main source of irrigation water is the Musi River, which collects a large volume of wastewater and stormwater while running through the city. From 1989 to 2002, the wastewater irrigated area along the Musi River increased from 5,213 to 8,939 ha with concurrent expansion of the city boundaries from 22,690 to 42,813 ha and also decreased barren lands and range lands from 86,899 to 66,616 ha. Opportunistic shifts in land use, especially related to wastewater irrigated agriculture, were seen as a response to the demand for fresh vegetables and easy access to markets, exploited mainly by migrant populations. While wastewater irrigated agriculture contributes to income security of marginal groups, it also supplements the food basket of many city dwellers. Landsat ETM + data and advanced methods such as spectral matching techniques are ideal for quantifying urban expansion and associated land use changes, and are useful for urban planners and decision makers alike.
A multiobjective optimization model has been presented for allocating irrigation waters in a rice paddy area. Water-saving practices conducted on the field-plot basis are considered and expressed in the optimal water allocation problem in the regional scale. Irrigation water allocated to the blocks of paddy fields is divided into two components of a basic amount and a safety margin in order to mitigate the effect of hydrological and hydraulic uncertainties on the study area. Four competing management objectives with regard to total rice yield, total water-saving cost, equity of water allocation, and safety of water supply are defined in the linear programming formulation so that noninferior solutions can be procured which are informative and persuasive in decision-making. Applicability of the optimization model is examined using water allocation problems for a hypothetical irrigation system. It is demonstrated that the optimization model can provide satisficing solutions where the four objectives are harmonized under substantial variations of total water supply to the irrigation system.
Various indicators are used for evaluating the performance of different aspects of an irrigation system, and assessments also differ in terms of the types of performance indicators used. This paper describes a GIS-based assessment system which utilizes a new concept and evaluated the inadequacy of a widely used Relative Water Supply (RWS) concept to characterize the irrigation delivery performance for a rice irrigation system as the season advances. Development of this GIS-based assessment system resulted in the creation of new indicators, viz., the Rice Relative Water Supply (RRWS), Cumulative Rice Relative Water Supply (CRRWS) and Ponding Water Index (PWI). These indicators were determined from field tests and evaluated in a Malaysian Tanjung Karang Rice Irrigation Scheme (TAKRIS). The RWS concept was found to be inaccurate for characterizing the oversupply condition on irrigation deliveries for rice irrigation; and difficult to correctly quantify the oversupply condition for irrigation supplies. Besides, it was found that the RRWS indicator can distinctly characterize the oversupply condition for RRWS > 1.0 and undersupply condition for RRWS < 1.0 on irrigation delivery for any given period. A value of 1.0 for RRWS indicates an irrigation delivery that matches perfectly the actual field water demand. This study presents a cumulative RRWS plot that provides important information on irrigation supplies for any given time interval for management decisions. An increasing slope in the actual CRRWS curve with CRRWS = 1.0, means that irrigation supply can be slightly curtailed in the next period. On the other hand, if the slope is negative, supply has to be increased. If a computed CRRWS line follows the CRRWS = 1.0 line, it means that irrigation deliveries are perfectly matched with the field water demand. A graphical user-interface was developed for structuring the assessment tool within an ArcGIS platform. The system can instantly provide information on the uniformity of water distribution and the shortfall or excess, and provides vital information in terms of decisions that need to be made for the next period. The system helps to maintain continuous updating of input and output databases on real field conditions. Results are displayed on the computer screen together with color-coded maps, graphs and tables in a comprehensible form. The system is likely to be adopted for evaluating various water allocation scenarios and water management options. It can also be used as an analytical and operational tool for irrigation managers.
In 2004, the Jordan National Water Master Plan (NWMP) was developed, which includes a number of water demand projection modules for assessing the existing water resources, and predicting demands on water for all uses; municipal, industrial, tourist and irrigation. The Irrigation Demand Module was tested with historical data and comparisons were made between the predicted demands as obtained by the module, and the recorded water use provided by relevant institutions. Serious imbalances appeared, totaling the irrigation water demands of more than 1.5 times the recorded irrigation water use. The purpose of this study was to verify the viability of the functional part of the Irrigation Demand Module, namely the Net Irrigation Requirements Calculator (NIR-Calculator) in terms of functions, factors, and data used for the calculations. Results show that the original NIR-Calculator overestimated the values of NIR in the initial growth stage, Kci, by almost 55 %, because Cuenca Formula is used in the original version to calculate the initial crop coefficient, while FAO-56 Formula is used in the modified version. When taking the Jordan climatic characteristic into consideration, the original NIR-Calculator underestimated the values of the mid growth stage crop coefficient, Kcm, by 1.7–3.5 %, as well as the values of the end growth stage crop coefficient, Kce, by 2.2–8.0 %. The original NIR-Calculator overestimated the effective rainfall by 66.5, 44.8 and 34 % for dry, medium and wet scenarios, respectively. The NIR values obtained by the original NIR-Calculator differed than the modified NIR-Calculator by 5.2, 6.2 and 8.6 % for dry, medium and wet scenarios respectively. Finally, the irrigation demand volume for Deir Ala area obtained by the original NIR-Calculator differed than the modified NIR-Calculator by 2.0, 3.5 and 9.3 % for dry, medium and wet scenarios respectively. In conclusion, although there is a difference between these two versions of the NIR-Calculator, this difference is not enough to cause the 1.5 imbalance in the Irrigation Demand Module. This imbalance can’t be attributed only to the NIR-Calculator and further investigation is required to determine why the imbalance exists.
Three parameters were introduced here, in the second paper of the series, to evaluate layout structure of multi-quality water supply networks for irrigation. The first parameter was flexibility, which assesses the capability for a flexible supply of variable water quality values which can be obtained by dilution inside the network facilities. The second was separability which expresses the capability of the network to be divided into separate isolated sub-networks, each carrying a different water quality. The third was rigidity, which expresses a rigid allocation of one to one source–consumer connections. Five types of network layout which were presented in Sinai (2011) were evaluated here, using these three parameters. The flexibility of a network was given special attention with the example of parallel and serial connection of fields to sources. A real example of a proposed network in the Hazeva region in Israel was analyzed. All feasible flow patterns (FFPs) were computed. The location of mixing and dilution junctions and computation of the QC feasibility domains were found and computed for every junction and consumer. Relative ranges of discharges and concentrations were conducted for all the FFPs found. However, no single optimal FFP with maximal flexibility was found. Therefore the FFPs were arranged in operational groups for possible sequential operation according to irrigation schedules.
In developing countries, natural river regimes are increasingly undergone human modifications. All these constraints strongly affect the river systems. However, study on minor tributary of modified river is few. Thus the interest of this paper is to explore a tributary due to extensively regulated flow regime of mainstem river constrained by two barrages. The mainstem and tributary are deteriorating in its water quality due to the existing estuarial barrage impoundment. However by inserting another barrage in the middle stretch, modelling efforts have shown that the fluvial quality in the tributary improves compared to the former conditions. This has indicated that barrage operations are offering chances of improving a constrained tributary in terms of flow, flushing capability and water quality.
As sources of irrigation water are decreasing, efficient use of surface irrigation is essential. The purpose of this study is to determine if partially-wetted furrow irrigation has more efficient water storage and infiltration than traditional border irrigation in an alluvial clay soil under cultivated grape production. The two irrigation components considered were wet (WT) and dry (DT) treatments, at which water was applied when available soil water reached 65 % and 50 %, and the traditional border irrigation control. Empirical power form equations were obtained for measured advance and recession times along the furrow length during the irrigation stages of advance, storage, depletion and recession. Coefficient of variation (CV) was 5.2 and 9.5 % for WT and DT under furrow irrigation system comparing with 7.8 % in border, respectively. Water was deeply percolated as 11.9 and 19.2 % for wet and dry furrow treatments respectively, compared with 12.8 % for control, with no deficit in the irrigated area. Partially-wetted furrow irrigation had greater water-efficiency and grape yield than dry furrow and traditional border irrigation, where application efficiency achieved as 88.1 % for wet furrow irrigation that achieved high grape fruit yield (30.71 Mg /ha). The infiltration (cumulative depth, Z and rate, I) was functioned to opportunity time (t 0 ) in minute for WT and DT treatments as: Z WT = 0.528 t 0 0.6, Z DT = 1.2 t 0 0.501, I WT = 19 t 0 −0.4, I DT = 36 t 0 −0.498. Empirical power form equations were obtained for measured advance and recession times along the furrow length during the irrigation stages of advance, storage, depletion and recession. The irrigation parameters and coefficients, and soil water distribution have been also evaluated.
Field experiments were performed to study the effect that wind shelterbelts has on irrigation uniformity of hand move sprinkler irrigation system located in northwest Kenya. Catch can tests were performed to evaluate the distribution of applied water using coefficient of uniformity and distribution uniformity for plots with shelterbelt and without shelterbelt scenarios. Three medium pressure twin nozzle sprinkler head types were tested to determine their water distribution uniformity at varying wind speed and working pressure and obtained results were statistically analysed. The analysis was used to ascertain the performance of the medium pressure sprinklers under varying wind conditions for the two scenarios. Results indicate that uniformity is improved by wind for wind speeds below 1.4 m/s. Analysis of data from sheltered and unsheltered plots showed a significant difference of uniformity parameters on sheltering with coefficient of uniformity for sheltered plots averaging 84 % compared to 74 % for unsheltered plots. Results indicate that the coefficient of uniformity values were higher than the distribution uniformity values although both had a strong linear relationship with a coefficient of determination above 0.96 in both scenarios. It is concluded that shelterbelts improve sprinkler irrigation performance under windy conditions.
This study aims to evaluate the potential effects of the climatic variations on the reference evapotranspiration (ET0) and, consequently, on the crop water requirements in the Apulian Tavoliere, one of the largest irrigated districts of Southern Italy. To reach this purpose, both climatic parameters (air temperature and rainfall) and estimated water requirements of ‘processing’ tomato (among the most representative irrigated crops in the district since the mid-1970s and, therefore, chosen as a study-case) were analyzed in order to find out if a time trend exists or does not. The analysis covered the period from 1957 to 2008. The analysis showed that the rainfall amounts decreased (−3.4 mm per year in the analyzed period), while air temperature increased (0.18 °C and 0.25−°C per decade for minimum and maximum, respectively). As a consequence of the climatic variation during the considered period, a growth trend of the ET0 (1.4 mm per year) and water deficit (3.2 mm per year) took place. As a consequence, the water amounts for irrigating the same crop in the considered period were growing. This increased consumption is in agreement with the perception of the farmers of the district but never documented. Through the FAO AquaCrop model, the tomato irrigation water requirements have been simulated during the considered period. The trend analysis of the seasonal evapotranspiration values simulated in 52 years confirmed the increase in tomato water requirements (0.7 mm per year).
This paper provides the methodology and results of a cross-scale diagnostic performance assessment program of the irrigation water management in the old lands of the Nile Delta of Egypt. The analysis was done at three levels; main canal level, branch canals level and on-farm level of the Meet Yazid command (82,740 ha) for the year 2008–2009 to highlight areas for improvement. At the main canal level the annual average percentage of irrigation water returning to drains and groundwater was 53% of the total water supplied. Since Meet Yazid lies at tail end of the delta, and there is groundwater salinity, opportunities for reuse are increasingly limited moving north to Lake Burullus. This would indicate opportunities for real water savings. The results of monthly relative water supply of the main canal indicated mismatch between demand and supply especially during the winter months, and when supply is low farmers do reuse drainage or groundwater. Also, the assessment of the three branch canals showed non-uniformity of water distribution and mismatch between demand and supply even when comparing improved and non-improved canals. At the on-farm level in paddy fields, the amount of irrigation flows to drains and saline sinks varied from 0.46 to 0.71 of inflow. In spite of these values of non-uniformity and low depleted fraction, the relative evapotranspiration (ratio of actual to potential) evaporation was uniformly high, indicating most crops of most farmers were not water stressed, which is also confirmed by the high yield values. The average values of productivity per unit water depleted by ETact were 1.04 and 1.05 kg/m3 for rice and wheat fields, respectively, with yields of rice and wheat at 8 and 6 t per ha respectively. On farm and tertiary improvements alone will not yield real water savings, as excess water in the main canal and drains will continue to flow out of the system. Rather the focus should first be on supplies to the main canal, accompanied by more precise on farm and water delivery practices at branch and tertiary levels, and ensuring that environmental flows are met. There is an added advantage of focusing on this tail end region of Egypt that this response would lessen vulnerability to reuse of polluted and saline water.
The affect of network structure on the performance of water supply systems of diverse water quality sources was assessed, using analytic methods. The analysis is presented in a series of 3 papers in which this paper is the first of the series. Five types of network structures were analyzed: i) single networks; ii) separate sub-networks; iii) multiple networks; iv) dilution networks; and v) combined dilution-separate networks. The properties of each network type were evaluated using the Q-C “Feasibility domain” (QCFD) concept, where discharge (Q) and concentration (C) are the major design parameters. The dilution network type was found most flexible and the single and separate network types were most rigid. The multiple network type provides certain flexibility, however it was exceptionally expensive. The improved network, which combined the advantages of the separate sub-networks with the dilution network was proposed and as an optimal design. The planning of such systems commenced with an initial analysis at the sources-consumers’ level without network facilities. The second stage required analysis of the various structures of the network layout. Ultimately, a layout was assumed and the effect of flow directions in that network was assessed for installation of back flow preventing devices, and improving the control of water quality. A rural region in southern Israel of 6 sources, 5 villages, and 8 fields was chosen. The 5 types of networks were planned for this region. The effect of network structure on the performance of these networks was analyzed and discussed.
